Three companies are vying to take on an upgrade of the undersea electricity link between the North and South Islands.
The new $700 million link will double the amount of electricity that can be transferred between the two islands.
Transpower chief executive Patrick Strange, says the current link is running at capacity, and the expansion project is seen as urgent by the entire electricity industry.
Dr Strange says the contract should be awarded later this year and the link should be completed in April, 2012.
The Domestic Energy Users Network says customers can expect more wild price changes until the link is completed.
The group says an independent review is needed in the meantime to examine spikes in prices and look at ways to make them more consistent for consumers and shareholders.